Schottky diodes are employed as rectifiers in numerous power and small signal applications where the forward conduction or switching characteristics of the diode are important. These diodes are used extensively as output rectifiers in switching-mode power supplies and in other high-speed power switching applications such as motor drives for carrying large forward currents. Ultra-low forward voltage drop (VF) under conduction and good blocking performance under a reverse bias are the desirable characteristics of an efficient Schottky diode.
One advanced design for a MOSFET to be used as a synchronous rectifier integrates a Schottky contact in each active cell of the transistor device. The Schottky contact clamps the internal body diode of the MOSFET to a voltage below 0.7V during conduction. The injection of minority carriers by the body diode is strongly suppressed, and the reverse recovery of the body diode is minimized.
Trench-MOS Barrier Schottky (TMBS) diodes are described in, for example, U.S. Pat. No. 5,365,102 to Mehrotra et al. and U.S. Pat. No. 6,078,090 to Williams et al., the entirety of each of which is hereby incorporated by reference herein. The Schottky diodes of these references shield the Schottky contact interface against a high electric field under reverse bias conditions, and by doing so allow an increase in the doping of the semiconductor material in the vicinity of the Schottky contact, which lowers the VF under conduction. Williams et al. discloses a trench-gated Schottky diode integrated with an internal clamping diode in the form of a trench MOSFET.
A Schottky diode is desired that can be monolithically integrated with other types of MOSFET devices.